Flood projects inch forward in Park Ridge

Park Ridge residents fill the city council chamber on Saturday, March 8 to discuss flood control. (Jon Davis, for the Chicago Tribune)

Work on three major flood control projects in Park Ridge inched forward recently at a weekend meeting packed with residents demanding relief.

Aldermen gave unanimous preliminary approval to begin drafting an inter-governmental agreement with the Metropolitan Water Reclamation District of Greater Chicago to join its sewer construction project slated for 2015 that would provide for drainage of stormwater from the Mayfield Estates neighborhood into the district's regional sewer under Dempster Street.

They also overwhelmingly gave preliminary approval to paying Christopher B. Burke Engineering up to $12,200 for work on detention basins for Northwest Park and for city officials to begin talking to their Park Ridge Park District counterparts about those plans. Ald. Marc Mazzuca was the lone "no" vote, saying he could not support it without knowing what the park district would accept.

The measures are scheduled to be considered for final approval at the city council's Wednesday meeting.

Aldermen also agreed by consensus to begin informal talks with the Park Ridge Country Club about its offer to help provide stormwater detention, to approach the Forest Preserve District of Cook County about potential new storm sewers to the Des Plaines River and to revisit in April the question of whether to seek a second opinion on Burke's proposed flood projects from other engineering firms.

The Rosemont-based Burke is drawing up three grading plans for stormwater detention basins at Northwest Park that can hold 40 acre-feet: maximum area/minimum depth, minimum area/maximum depth and one in between. An acre-foot is one acre of water one foot deep, equivalent to 325,851 gallons.

Informational discussions about how the city might pay for these projects (and others), and whether to create a citywide stormwater management master plan were postponed to April.

Burke officials estimate alleviating flooding in the Mayfair Estates neighborhood will cost between $1.8 million to $2.3 million, and in the Northwest Park neighborhood, $11.4 million to $28 million, depending on construction options.

Flood relief near the Park Ridge Country Club will cost between $23.1 million and $48.7 million because of topography and the fact that it's a nexus for three neighborhoods' sewer systems that all connect into the main 84-inch sewer under Sibley Avenue. That sewer carries stormwater and sewage to the Sibley Lift Station, which pumps excess water into the Des Plaines River.

But all that work would offer the area protection from 10-year storms only – a fact that so upset residents and aldermen that the council ordered a new query to Burke: what can be done to maximize flood protection above that level?

(The 10-, 50- and 100-year storm designations refer to the average occurrence of a storm. A 100-year storm, for example, means there is a 1 percent chance of a storm that large striking in any given year.)

Aldermen heard details of a new potential project that might help, if it's done in addition to the other projects proposed for the Country Club area. Burke engineers suggest detaching the sewers from an upstream neighborhood and piping that area's water directly to the Des Plaines River via a new "outfall" (outlet).

A full feasibility study of this idea would cost $359,000 and take a year to complete. But the first phase – consisting of a topography survey, feasibility of a new outfall at the river and whether the Forest Preserve District of Cook County would allow it – would cost $30,000. Further discussion of that proposal was deferred to April.

Burke has previously modeled the city's entire sewer system and watersheds and set out a schedule of flood-control projects whose first round is now entering its final phase.